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xiv                        FUR   SEALS   AND   HAIR   SEALS                      45 I
in six genera; but more generic names have been proposed. At
the other extreme stands Dr. Mivarfc, who speaks of only one
genus, Otaria; of this genus the number of species is by no
means agreed upon. There can, however, be no doubt of the
distinctness of the JSTorthern Fur Seal, O. wrsina (the " Seal" of
commerce and the cause of international complications), of the
Patagonian Maned Sea-Lion, O. jubata* of 0. pusilla* of the Cape,
of the Californian O, gillespiei, of O. Jiookeri from the Auckland
Islands, and of four or five others. The range of the genus is wide,
but is mainly Antarctic. It is usual to speak of " Hair Seals '*
and " Fur Seals," the latter being the species which produce the
" sealskin " of commerce. The difference is that in. the Fur Seals
there is a dense, soft under-fur, which is wanting in the other group.
It is, however, impossible to make this character the basis of a
generic subdivision. There is a Fur Seal, 0. nigrescens, in South
America as well as the more widely-known northern form.
Fam. 2. Tricfa.ecMd.ae.—This family contains but one genus,
Trichecfaus, the "Walrus or Morse, or Odobaenus, as the more
correct term seems to be. It is a tiresome result of accurate
conformity with the rules of priority in nomenclature that the
name Tricheehus should be applied to the Manatee. There is but
one species of Walrus, though it has been attempted to show that
the Pacific and Eastern forms are different. The animal is Arctic
and circumpolar. The Walrus is characterised by the enormous
canines of its upper jaw, which form the well-known tusks and
reach a length of 30 inches. The animal can progress on land
like the Sea-Lions; but, as in the Seals, there are no external
ears, though there is a slight protuberance above the meatus
auditorius. The strong bristles upon the upper lip are as thick as
crow quills. The pectoral limb has nails, but these are small, as
in the Sea-Lions. The under surface of the man us has a warty pad,
which cannot but assist2 in maintaining a foothold upon slippery
ice. The hind-limbs have longer nails, which are still diminutive
and subequal in size. There is no free tail. The liver of this
animal is much farrowed, but not so much so as in Otaria,, though
more so than in PJioca, The kidneys are of course lobulate, as in
the other aquatic Carnivores. The milk dental formula appears to
be If C t Pm + Mf. In the adult the formula3 is IŁ Of Mf.
* Murie, Trans. ZooL Sec. vii. 1894, p. 411,             a Of. the Dugong, p. 336.
* Kukenthal, Jen. ZeMschr. xscviit 1854, p. 76.